There is an Italian cafe in Islington that probably deserves British sport's version of a blue plaque. It was there, a decade ago, that two of its unsung heroes sat down to set the tone for all that followed at the Beijing and London Olympics.

Baroness Sue Campbell, then the newly appointed "reform chair" of the body that distributes lottery and exchequer cash to Olympic athletes, met over supper with Peter Keen, who had helped put British Cycling on the path to Olympic glory, but was by then working for Lucozade, to persuade him to take on the challenge.

"I told him I had a dream. I wanted to produce the best high-performance sports system in the world here, in Britain. But I said I couldn't do it without him. He didn't want to do it at first but a week later he rang and said: 'I'm in.'"

Between them they put in place the building blocks for the journey from 10th in the medal table in Athens to fourth in Beijing and then third in London.

The pair had met while conducting a government review of elite sport that was to form the template for UK Sport's uncompromising mission.

"I was very impressed with this mind of Peter's. A blue sky thinker, a visionary, who was very clear about what needed to happen. He was applying what he knew about cycling across the system," says Campbell, who is following Keen out of the door after he stood down as performance director before the London Games.

While the 10 years that followed would be far from smooth – punctuated by furious rows over budgets and the sort of petty turf wars that habitually hobble British sports administration – the upward trajectory was set.

If the first major step in that transformation had been John Major's introduction of Lottery funding in the wake of the humiliation of Atlanta in 1996, where Britain won a solitary gold and finished 36th in the medal table, the second was the overhaul of UK Sport instigated by Campbell.

The last piece in the jigsaw was arguably winning the right in 2005 to host the Games and the funding boost that followed, allowing it to pour in £312m over the London cycle and £347m in the four years to Rio 2016.

Now contemplating the end of her 10-year tenure – she will step down in May – the redoubtable Campbell has spent her life combining sport, education and the charitable sector.

A former PE teacher, then sports science lecturer, she was the chief executive of the National Coaching Foundation for a decade and then the chief executive of the Youth Sport Trust for a further 10 years.

Over the past decade, she poured all that experience and missionary zeal into revolutionising the elite sport system in this country and – through her continued chairmanship of the YST – banging the drum for the role sport can plan in schools and wider society. Campbell has ruffled feathers along the way but undoubtedly deserves the plaudits that flowed her way at a valedictory dinner last week.

In her YST office in a corner of Loughborough University's "SportPark", the flakes of snow tumbling past the windows serve as reminders that the giddy days of August and September 2012 are now long gone. She recalls how the foundations for that success were laid much earlier. When she was appointed as a "reform chair" of UK Sport, formerly the Sports Council of Great Britain, in 2003 she walked into an organisation that was "dysfunctional" with "major staffing issues" and a serious identity crisis.

"It was a very typical public sector culture – very concerned with process and not with output. We had endless committees and everything took a very long time."

Having overhauled the management team and empowered Keen to spread the gospel that had helped transform Britain's cyclists into potential world beaters to other sports, she also set about changing their culture.

Investment was remorselessly channelled at those sports and athletes most likely to win medals and efforts made to shake up the sometimes cosy and clubbable world of sports administration.

"At times people have felt the no-compromise approach is harsh. But it's enabled people to really understand what elite sport is about," says Campbell. "It isn't about giving everybody a chance. It is about homing in on those who can make it and helping them be the best they can be."

In 2005, Keen and Campbell walked into Gordon Brown's office and told him that they could come at least fourth in the medal table at London 2012 but that they would need commensurate funding. "In that 2005 meeting with government, we said we would win exactly 65 medals. It's there in the document," she says.

"We could justify that by saying that, in order to get those medals, we need these medallists and each of them cost this. Here's your bill. This is a business model, it's not an estimate." Once the totals were totted up at the closing ceremony, their prediction of 65 proved bang on.

Campbell, who was made a crossbench peer in 2003, has had to fight many battles along the way to protect her "Formula One" high-performance system. She recalls an early skirmish with Tessa Jowell over extending the four-year funding horizon to eight; then a post-Beijing battle with Jowell's successor Andy Burnham to fill a £100m hole in the budget that left her "pacing the house in despair" in the early hours of the morning.

More recently, she has seen off a proposed merger with the grassroots sport agency Sport England as part of Cameron's damp-squib "bonfire of the quangos" that she feared would dull UK Sport's focus. "I don't like conflict, believe it or not. My sister wonders how I can do this job because I shy away from it. I know people who have seen me at work will think that's a complete fib," she laughs.

"But my father used to say that if you don't stand for something you stand for nothing. And my job is to do what's right for sport. I might not be the easiest character to work with but I will fight and fight and fight for what is right."

More recently, her success in helping to persuade even Michael Gove of the merits of ring-fencing investment in school sport must stand among her biggest achievements. "People often refer to the fact I'm incredibly resilient. You can knock me down but I'll come back, I'm like a bouncing ball. The mission is worth the fight," says the 64-year-old.

The highs have been more than worth the lows. Campbell recalls the "amazing excitement" of being part of the delegation in Singapore in 2005 that won the 2012 Games for London and the "huge significance" of the breakthrough in Beijing, where up to 14 UK Sport staff slept on the floor of a city centre apartment by night and watched the medals roll in by day.

"At one point you were pinching yourself and thinking 'crikey, it's happening too soon'. It was a bit like watching the flowers come out in springtime," she says.

But she could not have scripted a denouement like London. From carrying the Olympic torch through her home village to sitting beside the prime minister as the medals rained in, and naturally taking the opportunity to lobby him to guarantee UK Sport's funding to Rio 2016, it was quite a postscript.

"There is so much that elite sport gives this country. I've never felt this nation like it was in the summer. There was a sense of national pride. We actually believed that if you stick us against the rest of the world, we're pretty good," she says.

"I'll never live through moments like that again. It was extraordinary. I was proud of the system, I was proud of the athletes. But I was so proud that when they sat in front of the media they projected the thing I value most about sport – its values. Humility, hard work, bouncing back from setbacks. I really believe sport changes lives."

Campbell says you'd have to be a "pretty strange creature" not to believe in the rationale for public investment in elite sport after London 2012, and is convinced it left politicians of all hues convinced of the need to protect it, even in austere times.

But her experiences with the International Inspiration programme that have left her office studded with mementoes from around the world have left her convinced that we are still failing at home to practise what we preach abroad about sport's wider role.

"We're still not as convinced about sport as a tool for development within this country as we are abroad. We have used sport to tackle HIV, community cohesion, gang warfare – it has changed people's lives," she says. "But we somehow don't quite believe it still. This notion of using sport as a tool to tackle wider social issues – at a political level people still aren't convinced it can drive massive social change."

It is a mission that she is unlikely to abandon given her myriad remaining roles within sport, but she insists that, as far as UK Sport goes, she leaves the organisation – and British Olympic sport – in good hands.

"That's the thing for me. London was wonderful. But that would mean nothing to me if the system wasn't strong," she says, refusing to turn wistful. "Yes, we can get better. But I'll be leaving them on an upward trajectory, and that's really exciting. I'll be watching on as they go on and do even greater things in Rio."